Hall's Milkvetch

Pisophaca hallii (A. Gray) Rydberg
Astragalus Hallii A. Gray, Proc. Am. Acad. 6: 224. 1864. Tragacanlha Hallii Kuntze, Rev. Gen. 945. 1891.
Astragalus gracilentus Hallii M. E. Jones, Contr. W. Bot. 8: 13. 1898. Homalobus Hallii Rydb. Bull. Torrey Club 32: 667. 1905.
A cespitose perennial, with a woody root; stems numerous, sometimes partly under ground, 3-5 dm. long, decumbent, fexuose, branched, striate, sparingly strigose, 3-6 dm. long; leaves spreading, 5-10 cm. long, the rachis strigose; stipules lance-deltoid, 3-4 mm. long; leaflets 13-23, oblong or elliptic, cuneate at the base, rounded, truncate, or retuse at the apex, glabrous above, strigose beneath, 5-15 mm. long, 2-6 mm. wide; peduncles erect, 4-12 cm. long; racemes 3-8 cm. long; bracts subulate 2-3 mm. long, sometimes often purple-tinged, the tube 5 mm. long, 2.5 mm. thick, the teeth unequal, deltoid, about 1 mm. long; corolla 12-15 mm. long, purple; banner decidedly arcuate; wings slightly shorter, the blade broadly oblanceolate, about equaling the claw, with a reflexed auricle; keel-petals broader and shorter, the blade semi-orbicular, shorter than the claw; pod oblanceolate-ellipsoid, slightly broader above the middle, terrete, short-stipitate, acute at each end, glabrous, about 2 cm. long, 5-6 mm. wide and thick; seeds brown, obliquely reniform, 2 mm. long.
Type locality: Valleys of the Rocky Mountains of Colorado. Distribution: Mountains of Colorado.

Perennial, Herbs, Stems woody below, or from woody crown or caudex, Plants with rhizomes or suckers, Taproot present, Nodules present, Stems erect or ascending, Stems or branches arching, spreading or decumbent, Stems prostrate, trailing, or mat forming, Stems less than 1 m tall, Stems solid, Stems or young twigs sparsely to densely hairy, Leaves alternate, Leaves petiolate, Stipules conspicuous, Stipules membranous or chartaceous, Stipules persistent, Stipules connate to each other, forming a tuber or sheath, Leaves compound, Leaves odd pinnate, Leaf or leaflet margins entire, Leaflets opposite, Leaflets 10-many, Leaves hairy on one or both surfaces, Inflorescences racemes, Inflorescence axillary, Bracts very small , absent or caducous, Flowers zygomorphic, Calyx 5-lobed, Calyx gibbous, inflated, or spurred, Calyx glabrous, Petals separate, Corolla papilionaceous, Petals clawed, Petals white, Petals blue, lavander to purple, or violet, Banner petal narrow or oblanceolate, Wing petals narrow, oblanceolate to oblong, Wing tips obtuse or rounded, Keel petals auriculate, spurred, or gibbous, Keel tips obtuse or rounded, not beaked, Stamens 9-10, Stamens diadelphous, 9 united, 1 free, Filaments glabrous, Style terete, Style persistent in fruit, Fruit a legume, Fruit unilocular, Fruit freely dehiscent, Fruit oblong or ellipsoidal, Fruit or valves persistent on stem, Fruit exserted from calyx, Fruit inflated or turgid, Fruit beaked, Fruit glabrous or glabrate, Fruit hairy, Fruit 11-many seeded, Seeds cordiform, mit-shaped, notched at one end, Seed surface smooth, Seeds olive, brown, or black.

Astragalus hallii is a species of milkvetch in the family Fabaceae.